natural hazardPPT课件
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A natural disaster is the effect of a natural hazard (e.g., flood, tornado, hurricane, volcanic eruption, earthquake, or landslide) that affects the environment, and leads to financial, environmental and/or human losses. The resulting loss depends on the capacity of the population to support or resist the disaster, and their resilience This understanding is concentrated in the formulation: "disasters occur when hazards meet vulnerability.
Fire, which for the most part bounds the Pacific
Plate. Many earthquakes happen each day, few of
which are large enough to cause significant
daof the nature hazards
• Geological hazards • Climatic and atmospheric hazards • Wildfire hazard • Disease
3
Geological hazards
• Avalanche:
• An avalanche is a geophysical hazard, (a slide of a large snow (or rock) mass down a mountainside), which will be caused when a buildup of snow is released from a slope. it is one of the major dangers faced in the mountains in winter. An avalanche is an example of a gravity current consisting of granular material. In an avalanche, lots of material or mixtures of different types of material fall or slide rapidly under the force of gravity. Avalanches are often classified by what they are made of.
earthquake in 1906
largest) take place in the 40,000-km-long,
horseshoe-shaped zone called the circum-Pacific
seismic belt, also known as the Pacific Ring of
Geological hazards
Lahar
• A lahar is a type of natural disaster closely related to a volcanic eruption, and involves a large amount of material, including mud, rock, and ash sliding down the side of the volcano at a rapid pace. These flows can destroy entire towns in seconds and kill thousands of people.
9
Geological hazards
• Landslides and mudflows
• A landslide is a disaster closely related to an avalanche, but instead of occurring with snow, it occurs involving actual elements of the ground, including rocks , trees, parts of houses, and anything else which may happen to be swept up. Landslides can be caused by earthquakes, volcanic eruptions, or general instability in the surrounding land. Mudslides, or mudflows, are a special case of landslides, in which heavy rainfall causes loose soil on steep terrain to collapse and slide downwards (see also lahar).
may be manifested by a shaking or displacement
of the ground and sometimes tsunamis. Most of San Franciscowas the world's earthquakes (90%, and 81% of the devastated by an
4
5
Geological hazards
Earthquake
• An earthquake is a phenomenon that results from
a sudden release of stored energy that radiates
seismic waves. At the Earth's surface, earthquakes
natural disaster
1
The definition
A natural disaster is a threat of a naturally occurring event that will have a negative effect on people or the environment. Many natural disasters are interrelated, e.g. earthquakes can cause tsunamis and drought can lead directly to famine.
Fire, which for the most part bounds the Pacific
Plate. Many earthquakes happen each day, few of
which are large enough to cause significant
daof the nature hazards
• Geological hazards • Climatic and atmospheric hazards • Wildfire hazard • Disease
3
Geological hazards
• Avalanche:
• An avalanche is a geophysical hazard, (a slide of a large snow (or rock) mass down a mountainside), which will be caused when a buildup of snow is released from a slope. it is one of the major dangers faced in the mountains in winter. An avalanche is an example of a gravity current consisting of granular material. In an avalanche, lots of material or mixtures of different types of material fall or slide rapidly under the force of gravity. Avalanches are often classified by what they are made of.
earthquake in 1906
largest) take place in the 40,000-km-long,
horseshoe-shaped zone called the circum-Pacific
seismic belt, also known as the Pacific Ring of
Geological hazards
Lahar
• A lahar is a type of natural disaster closely related to a volcanic eruption, and involves a large amount of material, including mud, rock, and ash sliding down the side of the volcano at a rapid pace. These flows can destroy entire towns in seconds and kill thousands of people.
9
Geological hazards
• Landslides and mudflows
• A landslide is a disaster closely related to an avalanche, but instead of occurring with snow, it occurs involving actual elements of the ground, including rocks , trees, parts of houses, and anything else which may happen to be swept up. Landslides can be caused by earthquakes, volcanic eruptions, or general instability in the surrounding land. Mudslides, or mudflows, are a special case of landslides, in which heavy rainfall causes loose soil on steep terrain to collapse and slide downwards (see also lahar).
may be manifested by a shaking or displacement
of the ground and sometimes tsunamis. Most of San Franciscowas the world's earthquakes (90%, and 81% of the devastated by an
4
5
Geological hazards
Earthquake
• An earthquake is a phenomenon that results from
a sudden release of stored energy that radiates
seismic waves. At the Earth's surface, earthquakes
natural disaster
1
The definition
A natural disaster is a threat of a naturally occurring event that will have a negative effect on people or the environment. Many natural disasters are interrelated, e.g. earthquakes can cause tsunamis and drought can lead directly to famine.